Filter device with releasably securable end cap and sealing arrangement

ABSTRACT

A filter device for fluids, especially for fuels such as diesel fuel, includes a filter housing ( 1 ) defining a longitudinal axis ( 19 ). The filter housing has a fluid inlet ( 14 ) and a fluid outlet ( 24 ) and can accommodate at least one filter element ( 9 ). The fluid can, during filtering, flow through a filter medium ( 11 ) surrounding an inner filter cavity. The filter element ( 9 ) is enclosed by an end cap ( 21 ) on its lower end facing the bottom part ( 5 ) of the filter housing ( 1 ). The end cap has a passage ( 29 ) forming a fluid connection to the inner filter cavity ( 17 ) and can be fixed to an element retainer ( 23 ) of the filter housing ( 1 ). The element retainer ( 23 ) includes retaining piece ( 35 ) on the bottom part ( 5 ) of the filter housing ( 1 ). The retaining piece is open towards the filter element ( 9 ) with a fluid channel ( 37 ) leading to a housing connection ( 24 ) running into it. The end cap ( 21 ) of the filter element ( 9 ) has a connecting piece ( 27 ) accommodated in the retaining piece ( 35 ) and secured in a supporting zone. The retaining piece ( 35 ) forms an opening ( 43 ) forming a fluid connection to the fluid channel ( 37 ) leading to the element retainer ( 23 ) and including a sealing arrangement ( 45, 47 ) sealing the opening from the open end of the retaining piece.

FIELD OF THE INVENTION

The invention relates to a filter device for fluids, in particular forfuels, such as diesel oil. The filter device comprises a filter housing,defining a longitudinal axis. The filter housing has housing connectionsin the form of a fluid inlet and a fluid outlet and can accommodate atleast one filter element. During the filtration operation, the fluid canflow through a filter medium enclosing an inner filter cavity. Thefilter element is enclosed by an end cap on the filter element's lowerend facing the bottom part of the filter housing. The end cap comprisesa passage forming a fluid connection to the inner filter cavity and canbe secured on an element retainer of the filter housing. The inventionalso relates to a filter element for use in that filter device.

BACKGROUND OF THE INVENTION

Filter devices of this type are known from the prior art. Such filterdevices are typically used in fuel systems for internal combustionengines to protect sensitive components, in particular the injectionsystems, against degradation due to impurities entrained in the fuel. Toguarantee that the systems downstream of the filter will operate withoutany trouble over their entire service life, the filter device has tosatisfy high reliability requirements. The operational reliability isgreatly affected by the properties of the connection between the end capand the element retainer. The filter element under consideration has tobe accurately positioned in the filter housing by the element retainer.A reliable, tightly sealed fluid connection to the filter cavity must beformed. In addition, when changing the filter element during the ongoingoperations, a flawless connection between the end cap and the elementretainer when the new filter element is installed must be ensured.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved filterdevice that is especially suited to meet the requirements underconsideration with respect to the operating behavior.

The present invention basically achieves this object with a filterdevice having an element retainer that has, according to the invention,a retaining piece located on the bottom part of the filter housing andopen in the direction of the filter element. A fluid channel leading toa housing connection empties into the retaining piece, with the end capof the filter element having a connecting piece. The cap connectingpiece can be accommodated in the retaining piece and can be securedtherein over a support zone having an axial length. In addition, theretaining piece has an opening forming a fluid connection to the fluidchannel emptying into the element retainer and has a seal arrangementsealing off the opening from the open end of the retaining piece. Sincethe filter element is secured in the element retainer by the connectingpiece of the end cap over a support zone that extends over an axiallongitudinal area, the filter element is guaranteed to be perfectlypositioned and secured in its place in the filter housing. Secondly, theconnecting piece forms a fluid duct in interaction with the retainingpiece of the element retainer by the opening in the connecting piece.This fluid duct connects the inner filter cavity to the assigned housingconnection, so that a reliably sealed fluid path is formed by the sealarrangement at the connecting piece. When the connecting piece isinserted into the retaining piece of the element retainer, the result isa reliable coupling between the end cap of the filter element and theelement retainer during replacement operations of the filter element.

Preferably, the axial length of the support zone is not less thanone-fourth of the diameter of the retaining piece.

The coupling between the end cap and the element retainer is designed tobe very easy and reliable, if, according to an advantageous exemplaryembodiment, the interior of the retaining piece has an insertion chamferthat diverges in the direction of the open end.

Especially advantageously, the seal arrangement is formed by sealingelements arranged on the exterior of the connecting piece at an axialdistance from each other that defines the length of the support zone.These sealing elements secure the connecting piece in the elementretainer by resting against the interior of the retaining piece of theelement retainer.

A particular advantage is that the connecting piece of the end cap canhave a closed bottom on its end that is to be accommodated in theelement retainer. In this case, the opening leading to the fluid channelis located in the wall of the connecting piece above this bottom. As aresult, the connecting piece forms with its closed lower end acollecting space between the bottom and the opening located in the wall.Any residual fluid that may have dripped out of the inner filter cavitywhen the filter element was removed remains in this collecting space.The risk of polluting the environment during removal of a filter elementis then reduced.

Especially preferably, the retaining piece of the element retainer isalso closed on its lower end by a bottom that forms a depression as thelowest point of the filter housing. As a result, a collecting space forthe residual fluid that drips off during the changing of the filter, orfor any dirt particles that may fall off is formed in the bottom part ofthe filter housing. In this case, these substances remain collected atthe lowest point of the housing, that is, below the fluid channel thatleads from the element retainer to the associated housing connection.

Preferably, during the filtration operation, the fluid can flow throughthe filter medium of the filter element from its outer unfiltered sideto the inner filter cavity forming the clean side. The fluid channelemptying into the retaining piece of the element retainer then leads tothe housing connection that serves as the fluid outlet.

The subject matter of the invention is also a filter element for use ina filter device.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses a preferredembodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a side elevational view in section of filter according to anexemplary embodiment of the invention; and

FIG. 2 is an enlarged partial perspective view in section of thesubregion of the filter device of FIG. 1 adjacent to the elementretainer of the filter housing.

DETAILED DESCRIPTION OF THE INVENTION

The filter device has a filter housing 1 comprising a main part 3 in theform of a hollow cylinder and a closed bottom part 5 connected to theunderside of the main part. At the upper end, a housing cover 7 isscrewed to the main part 3. This housing cover can be removed for thepurpose of installing and removing a filter element 9. In the exemplaryembodiment to be described herein, the filter element 9 can be traversedby flow from the outside to the inside. An intermediate space is locatedbetween the exterior of the filter element 9, accommodated in thehousing 1, and the inner wall of the housing 1 and forms the unfilteredside 13 during the filtration operation. A housing connection 14 leadsin the direction of the unfiltered side 13 and forms the fluid inlet.The filter medium 11 of the filter element 9 is formed by a filter mat,formed into a hollow cylinder. This filter mat surrounds afluid-permeable support tube 15 forming an inner filter cavity 17forming the clean side 16, in which the cleaned fluid may be found,during the filtration operation.

The respective end of the filter element is provided in the conventionalmanner with end cap 21 that forms enclosures for the filter medium 11and the support tube 15. The lower end cap 21 that locates the filterelement 9 in the functional position in the housing 1, can be secured inthe housing 1, forms both the anchoring element anchoring the filterelement 9 in an element retainer 23 on the bottom part 5 of the filterhousing 1, and forms a fluid-conducting device for providing a fluidconnection between the inner filter cavity 17 and the housing connection24 forming the fluid outlet in the illustrated example. For thispurpose, the lower end cap 21 has a connecting piece 27 forming apassage 29 in the direction of the inner filter cavity 17. Theconnecting piece 27 extends from the end cap bottom 31 forming a flatsupport face for the lower edge of the filter medium 11, both axiallyupward with a tube section 25 into the filter cavity 17 and axiallydownward away from the end cap bottom 31 The axial length of thisdownwardly extending part is larger than the diameter of the tubesection 25. The interior of the support tube 15 rests against theexterior of the tube section 25 of the connecting piece 27 that projectsinto the filter cavity 17. The end cap 21 forms, with the outercircumferential edge 33 of the end cap bottom 31, the outer enclosure ofthe filter medium 11.

The element retainer 23 has a retaining piece 35 on the bottom part 5 ofthe filter housing 1. This retaining piece is open on the upper endfacing the filter element 9 and accommodates the connecting piece 27 ofthe filter element 9 located in the functional position. The lower endof the retaining piece 35 is closed by a bottom part 49. Above thebottom part 49, a fluid channel 37, that leads to the fluid outlet 24and that extends transversely to the longitudinal axis 19 of the filterhousing 1, empties into the retaining piece 35 of the element retainer23. The interior of the retaining piece 35 of the element retainer 23forms an insert chamfer 39 that diverges in the direction of the openend of the retaining piece 35 and that facilitates the insertion of theconnecting piece 27 into the element retainer 23. The part of theconnecting piece 27 of the end cap 21 accommodated in the retainingpiece 35 is stepped in the outside diameter such that a fluid space 41,into which the fluid channel 37 empties, is formed between the retainingpiece 35 and the connecting piece 27.

In the illustrated example, the axial length of the part of theconnecting piece 27 that can be accommodated in the retaining piece 35is equal to approximately half the size of the diameter of the openingof the retaining piece 35. The wall of the retaining piece 27 has anopening 43 connecting the interior of the connecting piece 27 and, bythe passage 29, the filter cavity 17 to the fluid outlet 24 by the fluidchannel 37. As a result, a fluid duct is formed by the connecting piece27 of the lower end cap 21 from the clean side 16, located in the filtercavity 17, to the fluid outlet 24. The fluid space 41 is sealed by seals45 and 47 in the direction of the interior of the retaining piece 35 ofthe element retainer 23. These seals are located on the exterior of theconnecting piece 27 at an axial distance from one another. A supportzone is then formed proportionate to a large axial length for thepurpose of supporting the connecting piece 27 in the retaining piece 35.

In the illustrated example, the axial length of this support zone isequal to about one-half of the diameter of the opening of the retainingpiece 35. Since this support zone extends over an axial region and has alength that can also be smaller or larger than one-half of the openingdiameter of the retaining piece 35, a secure fit of the filter element 9in the element retainer 23 is guaranteed. Owing to the seals 45, 47, aseal is formed simultaneously between the clean side 16, to which thesealed fluid space 41 also belongs, and the above opposite unfilteredside 13 located in the main part 3 of the housing 1. At the same time,the sealing ring 45 is provided with a larger diameter than the sealingring 47. The wall 39 (insert chamfer) tapering downward in the form of acone in the direction of FIG. 2, extends, when viewed in the installedstate of the filter element, between the two seals 45 and 47. The sealsare in contact with the cylindrical wall sections connected at the topand the bottom of the insert chamfer 39. Owing to this arrangement, nootherwise conventional seal is needed between the outer circumferentialedge 33 of the lower end cap 21 and the inner wall of the housing. Aseal arrangement having a correspondingly large diameter can be omitted.Instead, sealing elements of smaller diameter in the form of O-rings asthe seals 45 and 47 at the connecting piece 27 can be used. As a result,less physical effort is required for installation, and the costs arelower, while at the same time the operational reliability is improved.

In the illustrated example, the lower end of the retaining piece 35 ofthe element retainer 23 forms with the closed bottom part 49 the lowestpoint at the bottom part 5 of the filter housing 1. When the filterelement 9 that is to be changed is removed, the resulting closed bottomdepression of the housing 1 forms a receiving space for any residualfluid that may have dripped off or for any dirt particles that may havefallen off. Therefore, these substances stay in a “safe zone” below thefluid channel 37 leading to the fluid outlet 24. The connecting piece 27of the end cap 21 is also closed on the lower end, lying opposite thefilter cavity 17, by a bottom part 51. As is evident from the figures,the opening 43, continuing the fluid path over the fluid channel 37 tothe fluid outlet 24, is located in the wall of the connecting piece 27above this bottom part 51. A receiving space is then also formed insidethe connecting piece 27. In this case, the residual fluid that undersome circumstances may drip out of the inner filter cavity 17 when thefilter element 9 is removed, stays inside this space formed at the endcap 21. When the filter element 9 is taken out, no residual fluid canthen drip off the closed lower end of the filter element 9 and pollutethe environment. Counter to the described direction of flow, the filterdevice can also be operated, if necessary, with minor structuralalteration measures, in the opposite direction of flow.

While one embodiment has been chosen to illustrate the invention, itwill be understood by those skilled in the art that various changes andmodifications can be made therein without departing from the scope ofthe invention as defined in the appended claims.

What is claimed is:
 1. A filter device for fluids, comprising: a filterhousing defining a longitudinal axis, having housing connections of afluid inlet and a fluid outlet, and having a bottom part; a filterelement accommodated in said filter housing, said filter element havinga filter medium through which the fluid can flow during a filtrationoperation and connected in fluid communication with said fluid inlet andsaid fluid outlet, said filter medium surrounding an inner filtercavity; an element retainer being in said filter housing and having aretaining piece located on said bottom part, said retaining piece havingan open end in a direction of said filter element and an insertionchamfer on an interior thereof diverging in a direction of said open endthereof; a fluid channel leading to one of said housing connections andending in said retaining piece; an end cap enclosing a lower end of saidfilter element facing said bottom part, said end cap including a passagehaving a fluid connection to said inner filter cavity and beingreleasably secured on said element retainer, said end cap having aconnecting piece received in said retaining piece and secured in asupport zone of said retaining piece, said connecting piece having anopening connected in fluid communication with said fluid channel toconnect said fluid channel to one of said filter housing connections,said end cap having a bottom underlying said filter medium, saidconnecting piece extending from said bottom in a direction away fromsaid filter medium, said connecting piece of said end cap having aclosed bottom on an axial end thereof accommodated in said elementretainer, said opening being located in a side wall of said connectingpiece extending above said closed bottom thereof and parallel to saidlongitudinal axis, said opening extending perpendicular to saidlongitudinal axis; and a seal located between and contacting saidconnecting piece and said retaining piece in said support zone sealingsaid opening from said open end of said retaining piece.
 2. A filterdevice according to claim 1 wherein said support zone has an axiallength equal to at least one-fourth of a diameter of said opening ofsaid connecting piece.
 3. A filter device according to claim 1 whereinsaid seal comprises first and second sealing elements arranged on anexterior of said connecting piece, axially spaced from one another alongsaid longitudinal axis at a distance substantially equal to an axiallength of said support zone and securing said connecting piece in saidelement retainer by engaging an interior of said retainer piece.
 4. Afilter device according to claim 1 wherein said retaining piece of saidelement retainer is closed on a lower end thereof by a closed bottom,said bottom forming a depression and being a lowest point of said filterhousing.
 5. A filter device according to claim 1 wherein fluid flowsthrough said filter medium from an outer unfiltered side to an innerfiltered side and into said inner filter cavity during the filtrationoperation, said outer unfiltered side being connected in fluidcommunication with said fluid inlet, said inner filtered side beingconnected in fluid communication with said fluid outlet; and said fluidchannel is connected to said fluid outlet in fluid communication.
 6. Afilter device for fluids, comprising: a filter housing defining alongitudinal axis, having housing connections of a fluid inlet and afluid outlet, and having a bottom part; a filter element accommodated insaid filter housing, said filter element having a filter medium throughwhich the fluid can flow during a filtration operation and connected influid communication with said fluid inlet and said fluid outlet, saidfilter medium surrounding an inner filter cavity; an element retainerbeing in said filter housing and having a retaining piece located onsaid bottom part, said retaining piece having an open end in a directionof said filter element; a fluid channel leading to one of said filterhousing connections and ending in said retaining piece; an end capenclosing a lower end of said filter element facing said bottom part,said end cap including a passage having a fluid connection to said innerfilter cavity and being releasably secured on said element retainer,said end cap having a connecting piece received in said retaining pieceand secured in a support zone of said retaining piece, said connectingpiece having a closed bottom on an axial end thereof and an openingbeing located in a side wall of said connecting piece extending abovesaid closed bottom and being in fluid communication with said fluidchannel to connect said fluid channel to said one of said filter housingconnections, said side wall extending parallel to said longitudinalaxis, said opening extending perpendicular to said longitudinal axis,said end cap including a bottom underlying said filter medium, saidconnecting piece extending from said bottom in a direction away fromsaid filter medium; and a seal located between and contacting saidconnecting piece and said retaining piece in said support zone sealingsaid opening from said open end of said retaining piece.
 7. A filterdevice according to claim 6 wherein said support zone has an axiallength equal to at least one-fourth of a diameter of said opening ofsaid connecting piece.
 8. A filter device according to claim 6 whereinsaid seal comprises first and second sealing elements arranged on anexterior of said connecting piece, axially spaced from one another alongsaid longitudinal axis at a distance substantially equal to an axiallength of said support zone and securing said connecting piece in saidelement retainer by engaging an interior of said retainer piece.
 9. Afilter device according to claim 6 wherein said retaining piece of saidelement retainer is closed on a lower end thereof by a closed bottom,said bottom forming a depression and being a lowest point of said filterhousing.
 10. A filter device according to claim 6 wherein fluid flowsthrough said filter medium from an outer unfiltered side to an innerfiltered side and into said inner filter cavity during the filtrationoperation, said outer unfiltered side being connected in fluidcommunication to said fluid inlet, said inner filtered side beingconnected in fluid communication to said fluid outlet; and said fluidchannel leads to said fluid outlet.
 11. A filter element for fluids,comprising: a filter medium through which the fluid can flow during afiltration operation, said filter medium surrounding an inner filtercavity and having a longitudinal axis; an end cap enclosing a lower endof said filter element facing said bottom part, said end cap including apassage having a fluid connection to said inner filter cavity and beingreleasably securable on an element retainer in a filter housing, saidend cap having a connecting piece, said connecting piece having a closedbottom and an opening being located in a side wall of said connectingpiece above said closed bottom and connected in fluid communication withsaid fluid channel, said side wall extending parallel to saidlongitudinal axis, said opening extending perpendicular to saidlongitudinal axis, said end cap including a bottom underlying saidfilter medium, said connecting piece extending from said bottom in adirection away from said filter medium; and a seal extending radiallyoutwardly on said connecting piece sealing said opening from an open endof the element retainer.
 12. A filter element according to claim 11wherein said seal comprises first and second sealing elements arrangedon an exterior of said connecting piece, axially spaced from one anotheralong a longitudinal axis of said filter medium.
 13. A filter elementaccording to claim 11 wherein fluid flows through said filter mediumfrom an outer unfiltered side to an inner filtered side and into saidinner filter cavity during the filtration operation, said outerunfiltered side being connectable to a fluid inlet, said inner filteredbeing connectable to a fluid outlet.
 14. A filter element according toclaim 11 wherein said end cap comprises a bottom underlying said filtermedium, said connecting piece depending from said bottom.